Fluid pressure brake control apparatus



March 20, 1951 J. A. CAMPBELL FLUID PRESSURE BRAKE CONTROL APPARATUSFiled Nov. 24; 1948 WOC . INVENTOR. JAMES A CAMPBELL AT TORNEY PatentedMar. 20, 1951 FLUID PRESSURE BRAKE CONTROL APPARATUS James A. Campbell,Berkeley, Calif., assignor to The Westinghouse Air Brake Company,Wilmerding, Pa., a corporation of Pennsylvania Application November 24,1948, Serial N 0. 61,808

6 Claims.

This invention relates to fluid pressure brake control apparatus andmore particularly to the i type employed on railway locomotives.

In controlling freight trains down long grades it is necessary to holdlight applications of brakes for a considerable length of time, due towhich, the brake shoes, as well as the tires of the driver wheels of alocomotive, have a tendency to become undesirably overheated, resultingin excessive wear and a possibility of loosening said tires.

The principal object of the invention is therefore the provision ofmeans adapted to be applied to locomotive brake equipment for soregulating an application of brakes on the locomotive as to obviate theabove difliculty.

Accordingly to this object, I provide a device adapted to be associatedwith a locomotive brake equipment for, under the condition abovementioned, automatically limiting the degree of braking of a train bythe locomotive to a reasonable, but less than normal degree, so as toobviate the above diificulty, but which will permit an increase in theshare of train braking by the locomotive to normal when a greater degreeof braking is required for slowing down or stopping the train.

Other objects and advantages will appear in the following more detaileddescription of the invention which is illustrated by the accompanyingdrawing, wherein Fig. 1 is a diagrammatic view, partly in section, of alocomotive fluid pressure brake apparatus embodying one form of theinvention and Fig. 2 is a diagrammatic, sectional view, at an enlargedscale, of a differential relay device forming a part of said apparatus.

DESCRIPTION As shown in the drawing, the locomotive brake apparatuscomprises an engineers automatic brake valve device I, a brakecontrolling valve device 2, a fluid pressure relay valve device 3, abrake cylinder device A, a brake pipe 5 adapted to be connected througha train and to which said brake valve device l and brake controllingvalve device 2 are connected, and a main reservoir 6 connected by a mainreservoir pipe 7 to said brake valve device I and said relay valvedevice 3. The structure so far mentioned may be conventional andwell-known, the brake valve device I being provided for varying thepressure of fluid in the brake pipe by use of an operating handle la,and the brake controlling valve device 2 being responsive to variationsin brake pipe pressure to provide fluid at a proportional pressure to abrake cylinder control pipe 9 leading to the relay valve device 3, thesupply of fluid being supplied from an auxiliary reservoir [0 or fromboth the auxiliary reservoir and an emergency reservoir 1 l.

The relay valve device 3 comprises a piston 12 at one side of whichthere is a chamber [3 adapted to receive fluid under pressure from pipe9 by way of a pipe Id. At the opposite side of piston I2 is a chamber 15open to a pipe is connected to the brake cylinder device 4. The relayvalve device also comprises an exhaust valve ll exposed on one side tothe chamber [5 and on the other side to atmosphere by way of passage l8,and further comprises a supply valve l9, one side of which is subject tofluid under pressure from pipe 7 and the opposite side being exposed tochamber I5. A valve spring 23 urges exhaust valve IT in the direction ofthe left hand toward its normal unseated position and a valve spring 2|urges supply valve 19 in the direction of the left hand toward itsnormal seated position, the force of spring 21 on the supply valve I9being preferably slightly greater than that of spring 29 in valve H. Alever 23 having its opposite ends arranged to engage and seat and unseatthe exhaust valve I! and supply valve l9, respectively, is connected atits center to a stem 22 projecting from piston l2.

According to the invention, a differential relay valve device 8 is addedto the brake apparatus above described for regulating the pressure offluid efiective in chamber 53 of the relay valve device 3 via pipe l2 inaccordance with the pressure of fluid provided in pipe 9 by operation ofthe brake controlling valve device 2, and hence in accordance with thedegree of reduction in pressure in brake pipe 5.

The differential relay valve device 8 comprises a casing having chambers24 and 25 containing valves 26 and 27, respectively. The valve 26 isprovided on one end of a sleeve 28 slidably mounted in the casing andhaving an axial through bore 29 and a seat 30 encircling the end of saidbore 29 which is open to chamber 25, said seat being provided forcooperation with valve 2? to close communication between chambers 24 and25. Adjacent valve 25 is an annular chamber 3! encircling the sleeve 28,the valve 26 controlling communication between said chamber and chamber24. The valve chambers 24 and 25 are open respectively by passages 32and 33 to pipe l4 and atmosphere, while the annular chamber 3| is openby a passage 34 to the main reservoir pipe I. A spring 35 contained inchamber 24 acts on valve 26 for urging it to its seat 36.

The differential relay valve device 8 further comprises a flexiblediaphragm 31 at one side of which is a chamber 38 open to the brakecylinder control pipe 9 by way of a passage 39. At the opposite side ofdiaphragm 31 is a chamber 40 containing a diaphragm follower M securedcentrally to the diaphragm 31 by a screw 42. The

follower 4! has a depending skirt portion Ma in slidable contact with awall of the casing and in which there is provided a port 58 forequalizing fluid pressures within and encircling same. The follower 4|also has a stem 43 slidably extending through a bore 44 in apartitionwall 45 into the chamber wherein it is connected to valve 21for moving said Valve with the diaphragm 31.

In chamber there is disposed acylinder 56 having a closed end engagingthe-partitionwall 45. A sealing ring 41 is laced between cylinder 50 andpartition wall 45 toprevent communication between chamber 40 andchamber; 25. oslidably mounted in the cylinder 5il is a piston #48 ofsmaller area than diaphragm 31, and. adapted to engage the skirt portionMe of follower'4i, an equalizing port 5'! in said piston opening. thespace within said skirt portion to the space encircling said;piston andthe. cylinder'50. Interposedbetween cylinder and piston48,is-a-precompressed spring 49 urgingsaid piston against the follower 4!with achosendegree of force, such for example, as to prevent movement ofdia- ,phragm 3'! by less than eight pounds pressure of will behereinafter described. The cylinder 50 and piston 48 are, provided withaligned axial bores 46 and 5|, respectively, through which the followerstem 43 slidably extends. Between the piston 48 and cylinder 50. is anatmospheric chamr ber 52 open through a passage 53 in'cylinder 5i],

and a passage 53a in the followerstem 43 to valve chamber 25 and thenceto atmosphere. A sealing ring 54, ispositionedbetween the cylinder 50andthe piston 48 to prevent communication between chamber 40 and chamber52. Likewise,,a sealing ring 55,.is placed between. the piston 48 andthe follower stem 43 to prevent communication between chamber 40 andchamber.52. Chamber. 49 containing piston48andcylinder 53 and encircling.same and open to :the adjacent face ofdiaphragm 37 is openthrough'arelatively ,small passage 56 to .passage32 :and pipe, [4.

OPERATION Charging o1" the equipment main. reservoir 6 .toathe. brake:pipe 5 by way of main reservoir pipe I and throughthe .usual brake .pipecharging portsiand. passages (not shown) in the automatic brake valvedevice I. iFluid under pressure thus supplied to the brakerpipe .5

.flows to the brake controlling valve devicei2. The .brake controllingvalve device..2 operates in response to supply of fluid underpressure:to the brakepipe in the .usual'manner to. supply fluid :under pressureto the auxiliary reservoir l0 and to the emergency reservoir II and alsoto establish communication between the brake cylinder control pipe 9 andthe atmosphere.

With the controlpipe 9. connected. to atmosphere, chambers38in thedifferential relayvalve device 8 is connected to atmosphere therethroughto permit spring 49 to move piston 48 against follower 4| and move bothsaid piston and follower in an upwardly direction to the position inwhich they are. shown in the drawing, resulting in unseatingof-valve 121bystem 43 and seating of valve 26 by spring 35. This seating of valve 25agdisconnects the main reservoir pipe I from the delivery chamber 24,while the opening of valve 121.connects said chamber and thereby pipe Hito atmosphere by way of passage 32, chamber 24, 'bore :29,.chamber .25and passage 33. With \pipe .l4 .connected to atmosphere, chamber E3 ;of-the :relay valve device 3 will likewise be connected to atmosphere byway of pipe l4 thereby permitting valve springs 20 and 25 to move;pistonl2 to the left-hand position and at the same time to unseat exhaustvalve lL-andto-seatrsUPPl Valve I9. With exhaust valve; llof the relayvalve device 3 unseated, the brake cylinderdevice 4 is connected-toatmosphere by way of pipe 16,. chamber l5,,past said valve'and through;passage I8;for releasing the locomotive brakes.

Automatic application of thebra lccs Upon a'reduction'in pressure inbrake pipe 5 eifected in the usual-manner by means of the automaticbrake valvedevice l,- the brake controlling valve device 2 operates inthe usual wellknown manner to cut off communication between pipe 9 andatmosphere and. to supply fluid from the auxiliary reservoir I0 orfromboth-the-auxiliary reservoiralU :and' the--emergency reservoir i lto the pipe 9 and thereby to the control chamber33 of thedifierential'relay valve device. 8, at a pressure corresponding to thereduction in 'brakepipe pressure. When the pressure of fluid thusprovided in chamber 38 increases to a degree(such-as eight pounds)sufficient to overcome the opposing force of spring 49, the diaphragmflexes downward and through the medium of the diaphragm follower 4| andthe follower-stem 43 seats the exhaust-valve 2'1 against the valveseat3B, thereby cutting off communication'from the delivery chamber24 to theexhaust chamber-25, followed by movement of sleeve "28 by said valve tomove valve 26 off of valve seat 35 for establishingcommunication'between the supply chamber3l and the delivery chamber 24,whereupon fluid under pressure present in the supply chamber-3 I fromthe main reservoir pipe '5 flows past the valve.26 and through thedelivery chamber 24 to the delivery line 32 and thence'to chamber'l3 oftherelay valvedevice 3 by way of pipe 14.

As fluid under pressure is thus supplied to the -deliveryline 32and'chamber' l3 of the relay valve device 3; fluid-will also flow fromsaid line through the relativelysmall'passage 56 into chambers 46-and59, said passage-being relatively small to sorestrict supply of fluidunder pressure to said chambers as to permit thepressure of fluid inchamber 13 of the relay-valve device 3 to increase substantially inunison with the increase in qpressure-in chambers'40 and 59.

When fluid underrpressure is supplied to chambers! and 59 asjust'mentioned it will act in one -direction--against diaphragm 31 inopposition to "pressurelof fluid-in chamber 38 andin the oppositedirection .on theexposed face of piston-48 the-opposite face of which issubject to atmosphericpressure inchamber .52. Hence as fluidunderpressure is=suppliedto chamber 40, the pressure of :springc49 ondiaphragm 31 will be merit of diaphragm 31.

reduced in accordance with the pressure of such fluid acting on piston43, until at a chosen pressure of fluid in chamber 40, such as thirtyfive pounds, the piston 48 will move out of contact with follower 4!against said spring and completely remove pressure of said spring fromdiaphragm 37.

Assuming that the reduction in pressure in brake pipe 5 is such that thebrake control valve device 2 operates to provide in pipe 9 fluid ateight pounds pressure or less, the spring 49 in the difierential relayvalve device 8 will prevent move- If such pressure is increased to tenpounds, the diaphragm 31 will operate as above described to open thesupply valve 25 and supply fluid to chamber i3 in the relay valve device3 and to chambers 40 and 59 of the differential relay valve device 8until the pressure of such fluid acting on diaphragm 31, plus thecorrespondingly reduced effect of spring 49 (due to such pressure actingon the smaller area of piston 48), is increased to a degree suflicientto overcome the opposing pressure of fluid in chamber 38, whereupon thediaphragm 31 will be deflected against the latter pressure to permitclosure of valve 26 by spring 35 therebylimiting the pressure of fluidobtained in chamber [3 of the relay valve device 3 to a degree (such astwo pounds) corresponding to the reduced efiectiveness of spring 49. Ifthe pressure of fluid provided in chamber 38 be twenty pounds, thesupply valve 26 will close when the pressure of .fluid obtained inchamber [3 increases to, for

example, twelve pounds. If the pressure of fluid in chamber 38 isincreased to thirty five pounds or to any higher degree up to andincluding that (fifty pounds) usually obtained upon a full servicereduction in brake pipe pressure, the pressure of fluid obtained inchamber 40 and acting on piston 48 will overcome and move said pistonrelative to diaphragm 31 against spring 49 whereupon the supply valve 26will remain open until the pressure of fluid in chamber 38 is overcomesolely by the pressure of fluid in chambers 40 and 59, whereby thepressure of fluid in chambers 413 and 59 and in chamber [3 of the relayvalve device 3 will equal substantially that provided in diaphragmchamber 38.

From the above description it will now be seen that if the reduction inpressure in brake pipe 5. is such as to provide eight pounds or lesspressure of fluid in diaphragm chamber 31 of the differential relayvalve device 8, diaphragm chamber l3 of the relay valve device 3 willremain open to atmosphere, but if the pressure of fluid in diaphragmchamber 31 is increased, fluid will be provided in chamber I3 of therelay valve device 3 at a pressure gradually increasing in accordancewith the increase in pressure in chamber 38 and the correspondingdiminishing effect of spring 49 on diaphragm 31, until at the chosenrelatively high pressure of fluid, such as thirty five pounds in chamber38, the spring 49 will become totally ineffective to oppose pressure offluid in chamber 38 on diaphragm 31 whereupon and for any furtherincrease in pressure of fluid in chamber 38, the pressure of fluid inchamber E3 of the relay valve device 3 will increase to substantiallythe same degree as provided in chamber 38.

The relay valve device 3 is operative to reproduce in the brake cylinderdevice 4 the pressure of fluid provided in chamber I3, in a well-knownmanner. Briefly however, when fluid under pressure is supplied tochamber I 3, the piston I2 moves to the right and through the medium ofpiston stem 22 and the rocker arm 23 causes the exhaust valve I! toseat, for cutting off communication of the brake cylinder device 4 toatmosphere by way of chamber [5, and unseats the supply valve [9 forestablishing communication between the main reservoir pipe I, which ischarged with fluid under pressure from the main reservoir 6, and chamberl5 which is connected to brake cylinder device 4 by way of pipe l6,whereupon fluid under pressure is permitted to flow to the brakecylinder device for applying the brakes. When the fluid pressure in thebrake cylinder device 4 and in chamber I5 acting on the right-hand faceof piston l2 then becomes increased to approximately the same degree asacting in chamber I3, the piston I2 will move to the left far enough topermit spring 21 to close the supply valve IQ for thereby limiting thepressure of fluid obtained in the brake cylinder device to substantiallythe same degree as provided in pipe I4.

Release after automatic application of the brakes it] and the emergencyreservoir II and to establish communication between pipe 9 and theatmosphere as hereinbefore described in connection with the charging ofthe equipment.

With pipe 9 vented to atmosphere, the chamber 35 of the differentialrelay device 8 will be vented. With these conditions, the fluid pressurein chambers 45 and 59 and the spring 49 will move the piston 48 and thediaphragm 31 to the normal position shown in Fig. 2 of the drawing inwhich position the fluid pressure in pipe It will be released toatmosphere by way of passage 32, chamber 24, bore 29, unseated valve 21,chamber 25 and passage 33. When pipe I4 is vented, chamber 53 of relayvalve device 3 will also be vented to atmosphere. With this condition,the fluid pressure in chamber :5 will move the piston H? to the left tothe position shown in Fig. 1 of the drawing to permit closing of thesupply valve Ed by spring 2i and opening of the release valve il byspring 26 for releasing fluid under pressure from the brake cylinderdevice 4 to release the brakes on the locomotive.

SUMMARY From the above description it will now be seen that when thebrakes on a train are held partially applied for a considerable lengthof time, as common in braking a train on long descending grades, thedifferential relay valve device 8 will act to hold the locomotive brakeseither released or applied to less than the usual degree dependent uponthe degree of reduction in brake pipe pressure, for thereby reducing theundesirable tendency of excessive wear and overheating of the locomotivebrake shoes and wheel tires resulting with locomotive brake equipmentsat present in use. The safety of the train is not however jeopardized atany time since the differential relay value deviceprovides forautomatically increasing the proportion of train braking done by thelocomotive up to the normal degree in case 7 'aereatersbrakingm ithetrainl w qu red' to p i 'de-sa.dequategcontrolthereof. It is to-ibe,espec allysnoted thatrthe eabove. dva ta a o ta ned nerely b-y addin-,the differential relay :valve; device 8 ;to theusual locomotive brakeapperatus,,-:as;above es ribcd- Ha ins 1 w id scribeds-my i v nt n, w I-;cla i m ,as :new ;and :desire to secure by Letters LEatent; is

1.;In a locomotivafluid pressure: brake equip- .zment, incomb nationg abrak ine; ra m s ;operable :by fluidrinder; pressure to effect anapmlicat-ion.ofebrakes, brak -.contro11ins. m ;sponsive to aareducti nfb a p p p u tosupply fluirtat ia pressure corresponding to the deg-re,e,of suchreduction, valve means controlling a communicationior; conveyingfluid under pres- :sure ;to :said brake :means, movable abutment -;meansz nerabl by .fiu :u pr sup- -.-plied ."by :said brak ont l n means toonzeratezs id va ;-.mean t :o ena id ommun c tion, and operable by fluidunder pressure supplied to said brake means to effect operation of saidvalve-means to close said communication, -precompressed spring meansforactin 011 Said .abutmentmeans iii-opposition topressure of fluid,suppliedbysaid brake ,controlling means, and pistonsmeans interposedbetween said movable .abutment-meanspnd vspring means subject topressure-of fluid insaidbralge means opposing pressure ofsaid springmeans.

.2. ;In alocomotive fluid pressure brake equipment,iin combinationaibrake pipe, brake means operable by fluid :under pressure, to effectan application oflbrakes, brake controlling means re- ,sponsiveto a,reduction in brake pipe pressure to supply fluidat ,aipressurecorresponding to the degree ,of such reduction, valve meanscontrolling a :communication for conveying fluid under pressureeto saidbrake means, movable abutment means exposed at one side to pressureot-fluid providedby said brake controlling means .andlatthe oppositeside to pressure of fluid in .achamber open to said brake means andoperable by the formerpressure to operate said valve :means to open saidcommunication, precompressed-springmeans insaid chamber adapted :to act:on said abutment means in cooperation with pressure of fluid therein toeffect operation of said valve vmeans to'close said communica-,tion,.and-a second'movable abutment interposed lbetweensaid springmeansia-nd the first named movable abutment subject opposingly topressure of ifluid in'said chamberand atmospheric pres- ,suleiforreducing thepressure of said ,spring means on the first named abutmentinaccordance with pressure of fluid in said chamber.

3. An apparatus :ior-delaying supply of fluid under pressure to a pipeleading to afluid pressure actuated brake applying means upon supplyof;fluid under. pressure to a second pipe by operation of a brakecontrolling device in response to a reduction in pressure in a brakepipe, compris- "ing in combination, a casing connected to said pipes, avalve in said casing controlling a fluid pressure supply communicationto the first named pipe, a movable abutment in said casing, means insaid casing subjecting one side of said abutment to pressure fluid, insaid second pipe for operating said valve to open said communication,and precompressed spring means in said casing actingv onsaid abutment inopposition to pressure fluidinfsaid chamber for efiecting operation ofsaid valve. to closesaid communication.

apparatusfordelaying supply of fluid 75 lunder pressurei-tol a pipe,leadingto 1a fluid pressur a tuate brake apply n m n upon upply :iQf1fiu-id u;nder preSSlll{e to 'aisecond pipe by, oper- ;,ation of -a br al;econtrolling device in response 5 tea reductionin pressure-inja'brakepipe, com- ..prising, in combination, acasing connected. tosaidpipes, a valve in said casing controlling afluid ;pressuresupp lycommunication to the first named pipe, a movable abutment in said.casing, means in 1 said :casingI;subi'ecting v one side of said abut-.ment to;,pres sure-of1 fluid in-lsaid second-pipefor operating; saidvalve to opensaid-communication, ,means; imsaid casing subjecting theopposite side "of; said abutment-topressure of fluid in the, firstna-rned, pipe,: precompressed spring means in said casing-acting, onsaid opposite side of said-abutmer t forpreventing operation of saidabutment landthereby said valve toopen said communication with'lessthamachosenpressure of fluid a t ne on @sa on sid ofh id: a u m nt; an a :secndimovable abutment; i zsai as n nte posed between the first namedabutment and :saidlspring ,means and V-subject opposingly ,to l

pressures of fluid in ,said flrstnamed pipe-rand atmosphere for reducingthe pressure of said spring .:means .7 on :said first named abutment:inproportion to the increase inpressurein said cflrstinamedpipe inexcess'ofesaid chosenpres- -Sures.

.5. In combinatiomfiuid pressure actuated brake applyingcmeans, a first;pipe, for, conveying fluid .1UHC161"DIESSUI8 to saidimeans, a brakepipe,-a-sec- 5 ondv pipe, ;brake 'applicationmeans operative upon:reductioninpressure in-said brake pipe to :supply :zfiuid at ;a;.proportional pressure to ..said

second: .pipe,;.-and az'brake application device con- -nected2tosaidfirst andsecond pipes comprising v.alve smeanse controlling :a,fluidlpressure supply communicatiorrtosaid first pipe,.a. movable abut-'ment arranged to, be operatedby. pressure ofifluid insaidhsecondpipe tooperate said .valve means ,to.open;said.communication1and means for pre-;.venting.movement bylsaid labutment by fluid from.-saidsecond-pipeatiless thana chosen pressure.

6.iIn combination, fluid pressure actuated 2 brake applying means,-..affirst pipe for. conveying fluidlunder pressure: to: said means, a brakepipe, a second pipe, brakeapplication.meansoperaautivesuponna;reductiongin pressure in .said brake -pipetosupply; fluid at a proportionalpressure'to said second pipe -and r ai.brake application deviceeconnectedlto saidifirstandsecond pipes compris- -.-ing ivalvei'means;controlling .a fluid pressure supiplyacommunicationito.said first pipe,.a movable labutment:arranged to be'loperated by. pressure of .fluidzinsaid-second pipe tor-operate; said valve -:means ito 31010611 saidcommunication, precom- -pressedispringlmeans :opposingopressure of fluidinssaid second ,pipe :acting :on said abutment-:means,.:and:meanaoperablerby pressure of fluid rirrsaid first; pipe toreduce :the opposing pressure of said; spring means: in' 'proportion tothe. pressure ofz'fluid in said firstpipe.

JAMESA. CAMPBELL.

,REFERENCES CITED The following :references are of record in the"file-of this patent:

'UNITED'STATES PATENTS ,N umber Name Date .2,25, 0 M Nea -T--' S 119412,29%601 ,-Hev vitt Sept. l, 1942 2,405,632 -{Baldwin -Aug.;13, 1946

